Background: Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a genetic arrhythmia syndrome characterized by adrenergically-triggered ventricular arrhythmias, syncope, and sudden cardiac death. Several small studies suggest that atrial arrhythmias (AAs) are common in patients with CPVT. Objective: To determine the incidence and type of AAs observed within a large, single-center cohort of CPVT cases as well as the efficacy and durability of AA-directed management. Methods: In this retrospective study, the electronic medical record of 129 patients (52% female; average age at diagnosis 20.8  15.3 years) with CPVT (95% with a putative CPVT1-causative RYR2 variant) between 01/2000 and 09/2019 were reviewed for electrocardiographic evidence of AAs. Clinical features and efficacy of pharmacologic and ablation therapy were assessed. Results: Overall, 10/129 (7.8%) CPVT patients, all RYR2 variant-positive, had evidence of an AA (atrial fibrillation/flutter in 6, atrial tachycardia in 3, and supraventricular tachycardia in 1). The median age at AA diagnosis was 23 (14.2-35.5) years. 8/10 of patients experienced symptoms attributed to their AA, including inappropriate shocks. All patients were trialed on anti-arrhythmics, including -blockers, and/or flecainide. Owing to drug failure (1/10), drug intolerance (1/10), or patient preference (2/10); 4/10 patients received an ablation. Over a median follow-up of 23.5 (4.5-63) months, no AA recurrences were observed. Conclusion: Compared to prior studies, the incidence of AAs in this large, single-center referral cohort of CPVT patients was substantially lower (7.8% vs. 26%-35%). Although larger multi-center studies are needed to confirm, this study suggests that ablation is efficacious and durable in CPVT-associated AAs.

Background: Some long QT syndrome (LQTS) patients experience breakthrough cardiac events (BCEs) despite maximal therapy. Small studies have shown that intentional permanent atrial pacing (IPAP) is beneficial in refractory LQTS. As such, we sought to determine the genotype-specific utilization and efficacy of IPAP in a single-center LQTS registry. Methods and Results: In this retrospective study, electronic medical records from 1,065 LQTS patients were used to identify individuals that received IPAP. Pre- and post-IPAP heart rate, heart rate-corrected QT (QTc) values, annual BCE rate, and IPAP-related complications were compared between genotypes. BCEs were defined as LQTS-associated syncope/seizures, ventricular arrhythmia (VA)-terminating ICD therapies, and sudden cardiac arrest/death. Overall, 52/1065 LQTS patients received adjunctive IPAP therapy [77% female; median age 18.5 (IQR 1-35.5) years; 73% with prior VA]. Over an average IPAP follow-up of 121  82 months, the average heart rate increased from 65.8  20.4 bpm to 78.9  17.1 bpm; (p<0.01) and the average QTc decreased from 533.4  66.6 ms to 488.3  52.4 ms; (p<0.01). The mean BCE rate dropped from 0.88 to 0.19 per patient-year (p=0.01), driven by a marked decrease in LQT2 patients (1.01 BCE/year to 0.02 BCE/year; p=0.003). No serious IPAP-related complications were observed. Conclusion: In high-risk LQTS patients, namely those with recalcitrant LQT2, IPAP appears to be a safe and efficacious adjunct therapy. The beneficial effects of IPAP may stem from attenuating the QTc and circumventing a pause-dependent trigger. Whether IPAP might obviate the need for an ICD in some instances warrants further study.